Allow CollectionViewModel/Controller queries without SectionIdentifier

ios/chrome/browser/ui/collection_view/collection_view_model.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef IOS_CHROME_BROWSER_UI_COLLECTION_VIEW_COLLECTION_VIEW_MODEL_H_
 #define IOS_CHROME_BROWSER_UI_COLLECTION_VIEW_COLLECTION_VIEW_MODEL_H_
 
 #import <UIKit/UIKit.h>
 
 @class CollectionViewItem;
@@ skipping 158 matching lines @@
 #pragma mark Query index paths from items
 
 // Returns whether |item| exists in section for |sectionIdentifier|.
 - (BOOL)hasItem:(ObjectType)item
     inSectionWithIdentifier:(NSInteger)sectionIdentifier;
 
 // Returns the index path corresponding to the given |item|.
 - (NSIndexPath*)indexPathForItem:(ObjectType)item
          inSectionWithIdentifier:(NSInteger)sectionIdentifier;
 
+// Returns whether |item| exists.
+- (BOOL)hasItem:(ObjectType)item;
+
+// Returns the index path corresponding to the given |item|.
+- (NSIndexPath*)indexPathForItem:(ObjectType)item;
+
 #pragma mark UICollectionView data sourcing
 
 // Returns the number of collection view sections.
 - (NSInteger)numberOfSections;
 
 // Returns the number of collection view items in the given section.
 - (NSInteger)numberOfItemsInSection:(NSInteger)section;
 
 @end
 
 #endif  // IOS_CHROME_BROWSER_UI_COLLECTION_VIEW_COLLECTION_VIEW_MODEL_H_